HTMLPurifier_Encoder   F
last analyzed

Complexity

Total Complexity 110

Size/Duplication

Total Lines 607
Duplicated Lines 0 %

Importance

Changes 0
Metric Value
eloc 265
c 0
b 0
f 0
dl 0
loc 607
rs 2
wmc 110

12 Methods

Rating   Name   Duplication   Size   Complexity  
A muteErrorHandler() 0 2 1
A __construct() 0 3 1
C iconv() 0 47 12
A unsafeIconv() 0 6 1
B unichr() 0 42 11
A iconvAvailable() 0 7 3
D cleanUTF8() 0 153 38
B convertToASCIIDumbLossless() 0 30 7
B testEncodingSupportsASCII() 0 43 11
A testIconvTruncateBug() 0 21 5
B convertFromUTF8() 0 32 11
B convertToUTF8() 0 35 9

How to fix   Complexity   

Complex Class

Complex classes like HTMLPurifier_Encoder often do a lot of different things. To break such a class down, we need to identify a cohesive component within that class. A common approach to find such a component is to look for fields/methods that share the same prefixes, or suffixes.

Once you have determined the fields that belong together, you can apply the Extract Class refactoring. If the component makes sense as a sub-class, Extract Subclass is also a candidate, and is often faster.

While breaking up the class, it is a good idea to analyze how other classes use HTMLPurifier_Encoder, and based on these observations, apply Extract Interface, too.

1
<?php
2
3
/**
4
 * A UTF-8 specific character encoder that handles cleaning and transforming.
5
 * @note All functions in this class should be static.
6
 */
7
class HTMLPurifier_Encoder
8
{
9
10
    /**
11
     * Constructor throws fatal error if you attempt to instantiate class
12
     */
13
    private function __construct()
14
    {
15
        trigger_error('Cannot instantiate encoder, call methods statically', E_USER_ERROR);
16
    }
17
18
    /**
19
     * Error-handler that mutes errors, alternative to shut-up operator.
20
     */
21
    public static function muteErrorHandler()
22
    {
23
    }
24
25
    /**
26
     * iconv wrapper which mutes errors, but doesn't work around bugs.
27
     * @param string $in Input encoding
28
     * @param string $out Output encoding
29
     * @param string $text The text to convert
30
     * @return string
31
     */
32
    public static function unsafeIconv($in, $out, $text)
33
    {
34
        set_error_handler(array('HTMLPurifier_Encoder', 'muteErrorHandler'));
35
        $r = iconv($in, $out, $text);
36
        restore_error_handler();
37
        return $r;
38
    }
39
40
    /**
41
     * iconv wrapper which mutes errors and works around bugs.
42
     * @param string $in Input encoding
43
     * @param string $out Output encoding
44
     * @param string $text The text to convert
45
     * @param int $max_chunk_size
46
     * @return string
47
     */
48
    public static function iconv($in, $out, $text, $max_chunk_size = 8000)
49
    {
50
        $code = self::testIconvTruncateBug();
51
        if ($code == self::ICONV_OK) {
52
            return self::unsafeIconv($in, $out, $text);
53
        } elseif ($code == self::ICONV_TRUNCATES) {
54
            // we can only work around this if the input character set
55
            // is utf-8
56
            if ($in == 'utf-8') {
57
                if ($max_chunk_size < 4) {
58
                    trigger_error('max_chunk_size is too small', E_USER_WARNING);
59
                    return false;
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60
                }
61
                // split into 8000 byte chunks, but be careful to handle
62
                // multibyte boundaries properly
63
                if (($c = strlen($text)) <= $max_chunk_size) {
64
                    return self::unsafeIconv($in, $out, $text);
65
                }
66
                $r = '';
67
                $i = 0;
68
                while (true) {
69
                    if ($i + $max_chunk_size >= $c) {
70
                        $r .= self::unsafeIconv($in, $out, substr($text, $i));
71
                        break;
72
                    }
73
                    // wibble the boundary
74
                    if (0x80 != (0xC0 & ord($text[$i + $max_chunk_size]))) {
75
                        $chunk_size = $max_chunk_size;
76
                    } elseif (0x80 != (0xC0 & ord($text[$i + $max_chunk_size - 1]))) {
77
                        $chunk_size = $max_chunk_size - 1;
78
                    } elseif (0x80 != (0xC0 & ord($text[$i + $max_chunk_size - 2]))) {
79
                        $chunk_size = $max_chunk_size - 2;
80
                    } elseif (0x80 != (0xC0 & ord($text[$i + $max_chunk_size - 3]))) {
81
                        $chunk_size = $max_chunk_size - 3;
82
                    } else {
83
                        return false; // rather confusing UTF-8...
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84
                    }
85
                    $chunk = substr($text, $i, $chunk_size); // substr doesn't mind overlong lengths
86
                    $r .= self::unsafeIconv($in, $out, $chunk);
87
                    $i += $chunk_size;
88
                }
89
                return $r;
90
            } else {
91
                return false;
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92
            }
93
        } else {
94
            return false;
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95
        }
96
    }
97
98
    /**
99
     * Cleans a UTF-8 string for well-formedness and SGML validity
100
     *
101
     * It will parse according to UTF-8 and return a valid UTF8 string, with
102
     * non-SGML codepoints excluded.
103
     *
104
     * Specifically, it will permit:
105
     * \x{9}\x{A}\x{D}\x{20}-\x{7E}\x{A0}-\x{D7FF}\x{E000}-\x{FFFD}\x{10000}-\x{10FFFF}
106
     * Source: https://www.w3.org/TR/REC-xml/#NT-Char
107
     * Arguably this function should be modernized to the HTML5 set
108
     * of allowed characters:
109
     * https://www.w3.org/TR/html5/syntax.html#preprocessing-the-input-stream
110
     * which simultaneously expand and restrict the set of allowed characters.
111
     *
112
     * @param string $str The string to clean
113
     * @param bool $force_php
114
     * @return string
115
     *
116
     * @note Just for reference, the non-SGML code points are 0 to 31 and
117
     *       127 to 159, inclusive.  However, we allow code points 9, 10
118
     *       and 13, which are the tab, line feed and carriage return
119
     *       respectively. 128 and above the code points map to multibyte
120
     *       UTF-8 representations.
121
     *
122
     * @note Fallback code adapted from utf8ToUnicode by Henri Sivonen and
123
     *       [email protected] at <http://iki.fi/hsivonen/php-utf8/> under the
124
     *       LGPL license.  Notes on what changed are inside, but in general,
125
     *       the original code transformed UTF-8 text into an array of integer
126
     *       Unicode codepoints. Understandably, transforming that back to
127
     *       a string would be somewhat expensive, so the function was modded to
128
     *       directly operate on the string.  However, this discourages code
129
     *       reuse, and the logic enumerated here would be useful for any
130
     *       function that needs to be able to understand UTF-8 characters.
131
     *       As of right now, only smart lossless character encoding converters
132
     *       would need that, and I'm probably not going to implement them.
133
     */
134
    public static function cleanUTF8($str, $force_php = false)
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134
    public static function cleanUTF8($str, /** @scrutinizer ignore-unused */ $force_php = false)

This check looks for parameters that have been defined for a function or method, but which are not used in the method body.

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135
    {
136
        // UTF-8 validity is checked since PHP 4.3.5
137
        // This is an optimization: if the string is already valid UTF-8, no
138
        // need to do PHP stuff. 99% of the time, this will be the case.
139
        if (preg_match(
140
            '/^[\x{9}\x{A}\x{D}\x{20}-\x{7E}\x{A0}-\x{D7FF}\x{E000}-\x{FFFD}\x{10000}-\x{10FFFF}]*$/Du',
141
            $str
142
        )) {
143
            return $str;
144
        }
145
146
        $mState = 0; // cached expected number of octets after the current octet
147
                     // until the beginning of the next UTF8 character sequence
148
        $mUcs4  = 0; // cached Unicode character
149
        $mBytes = 1; // cached expected number of octets in the current sequence
150
151
        // original code involved an $out that was an array of Unicode
152
        // codepoints.  Instead of having to convert back into UTF-8, we've
153
        // decided to directly append valid UTF-8 characters onto a string
154
        // $out once they're done.  $char accumulates raw bytes, while $mUcs4
155
        // turns into the Unicode code point, so there's some redundancy.
156
157
        $out = '';
158
        $char = '';
159
160
        $len = strlen($str);
161
        for ($i = 0; $i < $len; $i++) {
162
            $in = ord($str[$i]);
163
            $char .= $str[$i]; // append byte to char
164
            if (0 == $mState) {
165
                // When mState is zero we expect either a US-ASCII character
166
                // or a multi-octet sequence.
167
                if (0 == (0x80 & ($in))) {
168
                    // US-ASCII, pass straight through.
169
                    if (($in <= 31 || $in == 127) &&
170
                        !($in == 9 || $in == 13 || $in == 10) // save \r\t\n
171
                    ) {
172
                        // control characters, remove
173
                    } else {
174
                        $out .= $char;
175
                    }
176
                    // reset
177
                    $char = '';
178
                    $mBytes = 1;
179
                } elseif (0xC0 == (0xE0 & ($in))) {
180
                    // First octet of 2 octet sequence
181
                    $mUcs4 = ($in);
182
                    $mUcs4 = ($mUcs4 & 0x1F) << 6;
183
                    $mState = 1;
184
                    $mBytes = 2;
185
                } elseif (0xE0 == (0xF0 & ($in))) {
186
                    // First octet of 3 octet sequence
187
                    $mUcs4 = ($in);
188
                    $mUcs4 = ($mUcs4 & 0x0F) << 12;
189
                    $mState = 2;
190
                    $mBytes = 3;
191
                } elseif (0xF0 == (0xF8 & ($in))) {
192
                    // First octet of 4 octet sequence
193
                    $mUcs4 = ($in);
194
                    $mUcs4 = ($mUcs4 & 0x07) << 18;
195
                    $mState = 3;
196
                    $mBytes = 4;
197
                } elseif (0xF8 == (0xFC & ($in))) {
198
                    // First octet of 5 octet sequence.
199
                    //
200
                    // This is illegal because the encoded codepoint must be
201
                    // either:
202
                    // (a) not the shortest form or
203
                    // (b) outside the Unicode range of 0-0x10FFFF.
204
                    // Rather than trying to resynchronize, we will carry on
205
                    // until the end of the sequence and let the later error
206
                    // handling code catch it.
207
                    $mUcs4 = ($in);
208
                    $mUcs4 = ($mUcs4 & 0x03) << 24;
209
                    $mState = 4;
210
                    $mBytes = 5;
211
                } elseif (0xFC == (0xFE & ($in))) {
212
                    // First octet of 6 octet sequence, see comments for 5
213
                    // octet sequence.
214
                    $mUcs4 = ($in);
215
                    $mUcs4 = ($mUcs4 & 1) << 30;
216
                    $mState = 5;
217
                    $mBytes = 6;
218
                } else {
219
                    // Current octet is neither in the US-ASCII range nor a
220
                    // legal first octet of a multi-octet sequence.
221
                    $mState = 0;
222
                    $mUcs4  = 0;
223
                    $mBytes = 1;
224
                    $char = '';
225
                }
226
            } else {
227
                // When mState is non-zero, we expect a continuation of the
228
                // multi-octet sequence
229
                if (0x80 == (0xC0 & ($in))) {
230
                    // Legal continuation.
231
                    $shift = ($mState - 1) * 6;
232
                    $tmp = $in;
233
                    $tmp = ($tmp & 0x0000003F) << $shift;
234
                    $mUcs4 |= $tmp;
235
236
                    if (0 == --$mState) {
237
                        // End of the multi-octet sequence. mUcs4 now contains
238
                        // the final Unicode codepoint to be output
239
240
                        // Check for illegal sequences and codepoints.
241
242
                        // From Unicode 3.1, non-shortest form is illegal
243
                        if (((2 == $mBytes) && ($mUcs4 < 0x0080)) ||
244
                            ((3 == $mBytes) && ($mUcs4 < 0x0800)) ||
245
                            ((4 == $mBytes) && ($mUcs4 < 0x10000)) ||
246
                            (4 < $mBytes) ||
247
                            // From Unicode 3.2, surrogate characters = illegal
248
                            (($mUcs4 & 0xFFFFF800) == 0xD800) ||
249
                            // Codepoints outside the Unicode range are illegal
250
                            ($mUcs4 > 0x10FFFF)
251
                        ) {
252
253
                        } elseif (0xFEFF != $mUcs4 && // omit BOM
254
                            // check for valid Char unicode codepoints
255
                            (
256
                                0x9 == $mUcs4 ||
257
                                0xA == $mUcs4 ||
258
                                0xD == $mUcs4 ||
259
                                (0x20 <= $mUcs4 && 0x7E >= $mUcs4) ||
260
                                // 7F-9F is not strictly prohibited by XML,
261
                                // but it is non-SGML, and thus we don't allow it
262
                                (0xA0 <= $mUcs4 && 0xD7FF >= $mUcs4) ||
263
                                (0xE000 <= $mUcs4 && 0xFFFD >= $mUcs4) ||
264
                                (0x10000 <= $mUcs4 && 0x10FFFF >= $mUcs4)
265
                            )
266
                        ) {
267
                            $out .= $char;
268
                        }
269
                        // initialize UTF8 cache (reset)
270
                        $mState = 0;
271
                        $mUcs4  = 0;
272
                        $mBytes = 1;
273
                        $char = '';
274
                    }
275
                } else {
276
                    // ((0xC0 & (*in) != 0x80) && (mState != 0))
277
                    // Incomplete multi-octet sequence.
278
                    // used to result in complete fail, but we'll reset
279
                    $mState = 0;
280
                    $mUcs4  = 0;
281
                    $mBytes = 1;
282
                    $char ='';
283
                }
284
            }
285
        }
286
        return $out;
287
    }
288
289
    /**
290
     * Translates a Unicode codepoint into its corresponding UTF-8 character.
291
     * @note Based on Feyd's function at
292
     *       <http://forums.devnetwork.net/viewtopic.php?p=191404#191404>,
293
     *       which is in public domain.
294
     * @note While we're going to do code point parsing anyway, a good
295
     *       optimization would be to refuse to translate code points that
296
     *       are non-SGML characters.  However, this could lead to duplication.
297
     * @note This is very similar to the unichr function in
298
     *       maintenance/generate-entity-file.php (although this is superior,
299
     *       due to its sanity checks).
300
     */
301
302
    // +----------+----------+----------+----------+
303
    // | 33222222 | 22221111 | 111111   |          |
304
    // | 10987654 | 32109876 | 54321098 | 76543210 | bit
305
    // +----------+----------+----------+----------+
306
    // |          |          |          | 0xxxxxxx | 1 byte 0x00000000..0x0000007F
307
    // |          |          | 110yyyyy | 10xxxxxx | 2 byte 0x00000080..0x000007FF
308
    // |          | 1110zzzz | 10yyyyyy | 10xxxxxx | 3 byte 0x00000800..0x0000FFFF
309
    // | 11110www | 10wwzzzz | 10yyyyyy | 10xxxxxx | 4 byte 0x00010000..0x0010FFFF
310
    // +----------+----------+----------+----------+
311
    // | 00000000 | 00011111 | 11111111 | 11111111 | Theoretical upper limit of legal scalars: 2097151 (0x001FFFFF)
312
    // | 00000000 | 00010000 | 11111111 | 11111111 | Defined upper limit of legal scalar codes
313
    // +----------+----------+----------+----------+
314
315
    public static function unichr($code)
316
    {
317
        if ($code > 1114111 or $code < 0 or
318
          ($code >= 55296 and $code <= 57343) ) {
319
            // bits are set outside the "valid" range as defined
320
            // by UNICODE 4.1.0
321
            return '';
322
        }
323
324
        $x = $y = $z = $w = 0;
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325
        if ($code < 128) {
326
            // regular ASCII character
327
            $x = $code;
328
        } else {
329
            // set up bits for UTF-8
330
            $x = ($code & 63) | 128;
331
            if ($code < 2048) {
332
                $y = (($code & 2047) >> 6) | 192;
333
            } else {
334
                $y = (($code & 4032) >> 6) | 128;
335
                if ($code < 65536) {
336
                    $z = (($code >> 12) & 15) | 224;
337
                } else {
338
                    $z = (($code >> 12) & 63) | 128;
339
                    $w = (($code >> 18) & 7)  | 240;
340
                }
341
            }
342
        }
343
        // set up the actual character
344
        $ret = '';
345
        if ($w) {
346
            $ret .= chr($w);
347
        }
348
        if ($z) {
349
            $ret .= chr($z);
350
        }
351
        if ($y) {
352
            $ret .= chr($y);
353
        }
354
        $ret .= chr($x);
355
356
        return $ret;
357
    }
358
359
    /**
360
     * @return bool
361
     */
362
    public static function iconvAvailable()
363
    {
364
        static $iconv = null;
365
        if ($iconv === null) {
366
            $iconv = function_exists('iconv') && self::testIconvTruncateBug() != self::ICONV_UNUSABLE;
367
        }
368
        return $iconv;
369
    }
370
371
    /**
372
     * Convert a string to UTF-8 based on configuration.
373
     * @param string $str The string to convert
374
     * @param HTMLPurifier_Config $config
375
     * @param HTMLPurifier_Context $context
376
     * @return string
377
     */
378
    public static function convertToUTF8($str, $config, $context)
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378
    public static function convertToUTF8($str, $config, /** @scrutinizer ignore-unused */ $context)

This check looks for parameters that have been defined for a function or method, but which are not used in the method body.

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379
    {
380
        $encoding = $config->get('Core.Encoding');
381
        if ($encoding === 'utf-8') {
382
            return $str;
383
        }
384
        static $iconv = null;
385
        if ($iconv === null) {
386
            $iconv = self::iconvAvailable();
387
        }
388
        if ($iconv && !$config->get('Test.ForceNoIconv')) {
389
            // unaffected by bugs, since UTF-8 support all characters
390
            $str = self::unsafeIconv($encoding, 'utf-8//IGNORE', $str);
391
            if ($str === false) {
392
                // $encoding is not a valid encoding
393
                trigger_error('Invalid encoding ' . $encoding, E_USER_ERROR);
394
                return '';
395
            }
396
            // If the string is bjorked by Shift_JIS or a similar encoding
397
            // that doesn't support all of ASCII, convert the naughty
398
            // characters to their true byte-wise ASCII/UTF-8 equivalents.
399
            $str = strtr($str, self::testEncodingSupportsASCII($encoding));
400
            return $str;
401
        } elseif ($encoding === 'iso-8859-1' && function_exists('mb_convert_encoding')) {
402
            $str = mb_convert_encoding($str, 'UTF-8', 'ISO-8859-1');
403
            return $str;
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404
        }
405
        $bug = HTMLPurifier_Encoder::testIconvTruncateBug();
406
        if ($bug == self::ICONV_OK) {
407
            trigger_error('Encoding not supported, please install iconv', E_USER_ERROR);
408
        } else {
409
            trigger_error(
410
                'You have a buggy version of iconv, see https://bugs.php.net/bug.php?id=48147 ' .
411
                'and http://sourceware.org/bugzilla/show_bug.cgi?id=13541',
412
                E_USER_ERROR
413
            );
414
        }
415
    }
416
417
    /**
418
     * Converts a string from UTF-8 based on configuration.
419
     * @param string $str The string to convert
420
     * @param HTMLPurifier_Config $config
421
     * @param HTMLPurifier_Context $context
422
     * @return string
423
     * @note Currently, this is a lossy conversion, with unexpressable
424
     *       characters being omitted.
425
     */
426
    public static function convertFromUTF8($str, $config, $context)
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426
    public static function convertFromUTF8($str, $config, /** @scrutinizer ignore-unused */ $context)

This check looks for parameters that have been defined for a function or method, but which are not used in the method body.

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427
    {
428
        $encoding = $config->get('Core.Encoding');
429
        if ($escape = $config->get('Core.EscapeNonASCIICharacters')) {
430
            $str = self::convertToASCIIDumbLossless($str);
431
        }
432
        if ($encoding === 'utf-8') {
433
            return $str;
434
        }
435
        static $iconv = null;
436
        if ($iconv === null) {
437
            $iconv = self::iconvAvailable();
438
        }
439
        if ($iconv && !$config->get('Test.ForceNoIconv')) {
440
            // Undo our previous fix in convertToUTF8, otherwise iconv will barf
441
            $ascii_fix = self::testEncodingSupportsASCII($encoding);
442
            if (!$escape && !empty($ascii_fix)) {
443
                $clear_fix = array();
444
                foreach ($ascii_fix as $utf8 => $native) {
445
                    $clear_fix[$utf8] = '';
446
                }
447
                $str = strtr($str, $clear_fix);
448
            }
449
            $str = strtr($str, array_flip($ascii_fix));
450
            // Normal stuff
451
            $str = self::iconv('utf-8', $encoding . '//IGNORE', $str);
452
            return $str;
453
        } elseif ($encoding === 'iso-8859-1' && function_exists('mb_convert_encoding')) {
454
            $str = mb_convert_encoding($str, 'ISO-8859-1', 'UTF-8');
455
            return $str;
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456
        }
457
        trigger_error('Encoding not supported', E_USER_ERROR);
458
        // You might be tempted to assume that the ASCII representation
459
        // might be OK, however, this is *not* universally true over all
460
        // encodings.  So we take the conservative route here, rather
461
        // than forcibly turn on %Core.EscapeNonASCIICharacters
462
    }
463
464
    /**
465
     * Lossless (character-wise) conversion of HTML to ASCII
466
     * @param string $str UTF-8 string to be converted to ASCII
467
     * @return string ASCII encoded string with non-ASCII character entity-ized
468
     * @warning Adapted from MediaWiki, claiming fair use: this is a common
469
     *       algorithm. If you disagree with this license fudgery,
470
     *       implement it yourself.
471
     * @note Uses decimal numeric entities since they are best supported.
472
     * @note This is a DUMB function: it has no concept of keeping
473
     *       character entities that the projected character encoding
474
     *       can allow. We could possibly implement a smart version
475
     *       but that would require it to also know which Unicode
476
     *       codepoints the charset supported (not an easy task).
477
     * @note Sort of with cleanUTF8() but it assumes that $str is
478
     *       well-formed UTF-8
479
     */
480
    public static function convertToASCIIDumbLossless($str)
481
    {
482
        $bytesleft = 0;
483
        $result = '';
484
        $working = 0;
485
        $len = strlen($str);
486
        for ($i = 0; $i < $len; $i++) {
487
            $bytevalue = ord($str[$i]);
488
            if ($bytevalue <= 0x7F) { //0xxx xxxx
489
                $result .= chr($bytevalue);
490
                $bytesleft = 0;
491
            } elseif ($bytevalue <= 0xBF) { //10xx xxxx
492
                $working = $working << 6;
493
                $working += ($bytevalue & 0x3F);
494
                $bytesleft--;
495
                if ($bytesleft <= 0) {
496
                    $result .= "&#" . $working . ";";
497
                }
498
            } elseif ($bytevalue <= 0xDF) { //110x xxxx
499
                $working = $bytevalue & 0x1F;
500
                $bytesleft = 1;
501
            } elseif ($bytevalue <= 0xEF) { //1110 xxxx
502
                $working = $bytevalue & 0x0F;
503
                $bytesleft = 2;
504
            } else { //1111 0xxx
505
                $working = $bytevalue & 0x07;
506
                $bytesleft = 3;
507
            }
508
        }
509
        return $result;
510
    }
511
512
    /** No bugs detected in iconv. */
513
    const ICONV_OK = 0;
514
515
    /** Iconv truncates output if converting from UTF-8 to another
516
     *  character set with //IGNORE, and a non-encodable character is found */
517
    const ICONV_TRUNCATES = 1;
518
519
    /** Iconv does not support //IGNORE, making it unusable for
520
     *  transcoding purposes */
521
    const ICONV_UNUSABLE = 2;
522
523
    /**
524
     * glibc iconv has a known bug where it doesn't handle the magic
525
     * //IGNORE stanza correctly.  In particular, rather than ignore
526
     * characters, it will return an EILSEQ after consuming some number
527
     * of characters, and expect you to restart iconv as if it were
528
     * an E2BIG.  Old versions of PHP did not respect the errno, and
529
     * returned the fragment, so as a result you would see iconv
530
     * mysteriously truncating output. We can work around this by
531
     * manually chopping our input into segments of about 8000
532
     * characters, as long as PHP ignores the error code.  If PHP starts
533
     * paying attention to the error code, iconv becomes unusable.
534
     *
535
     * @return int Error code indicating severity of bug.
536
     */
537
    public static function testIconvTruncateBug()
538
    {
539
        static $code = null;
540
        if ($code === null) {
541
            // better not use iconv, otherwise infinite loop!
542
            $r = self::unsafeIconv('utf-8', 'ascii//IGNORE', "\xCE\xB1" . str_repeat('a', 9000));
543
            if ($r === false) {
544
                $code = self::ICONV_UNUSABLE;
545
            } elseif (($c = strlen($r)) < 9000) {
546
                $code = self::ICONV_TRUNCATES;
547
            } elseif ($c > 9000) {
548
                trigger_error(
549
                    'Your copy of iconv is extremely buggy. Please notify HTML Purifier maintainers: ' .
550
                    'include your iconv version as per phpversion()',
551
                    E_USER_ERROR
552
                );
553
            } else {
554
                $code = self::ICONV_OK;
555
            }
556
        }
557
        return $code;
558
    }
559
560
    /**
561
     * This expensive function tests whether or not a given character
562
     * encoding supports ASCII. 7/8-bit encodings like Shift_JIS will
563
     * fail this test, and require special processing. Variable width
564
     * encodings shouldn't ever fail.
565
     *
566
     * @param string $encoding Encoding name to test, as per iconv format
567
     * @param bool $bypass Whether or not to bypass the precompiled arrays.
568
     * @return Array of UTF-8 characters to their corresponding ASCII,
569
     *      which can be used to "undo" any overzealous iconv action.
570
     */
571
    public static function testEncodingSupportsASCII($encoding, $bypass = false)
572
    {
573
        // All calls to iconv here are unsafe, proof by case analysis:
574
        // If ICONV_OK, no difference.
575
        // If ICONV_TRUNCATE, all calls involve one character inputs,
576
        // so bug is not triggered.
577
        // If ICONV_UNUSABLE, this call is irrelevant
578
        static $encodings = array();
579
        if (!$bypass) {
580
            if (isset($encodings[$encoding])) {
581
                return $encodings[$encoding];
582
            }
583
            $lenc = strtolower($encoding);
584
            switch ($lenc) {
585
                case 'shift_jis':
586
                    return array("\xC2\xA5" => '\\', "\xE2\x80\xBE" => '~');
587
                case 'johab':
588
                    return array("\xE2\x82\xA9" => '\\');
589
            }
590
            if (strpos($lenc, 'iso-8859-') === 0) {
591
                return array();
592
            }
593
        }
594
        $ret = array();
595
        if (self::unsafeIconv('UTF-8', $encoding, 'a') === false) {
596
            return false;
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597
        }
598
        for ($i = 0x20; $i <= 0x7E; $i++) { // all printable ASCII chars
599
            $c = chr($i); // UTF-8 char
600
            $r = self::unsafeIconv('UTF-8', "$encoding//IGNORE", $c); // initial conversion
601
            if ($r === '' ||
602
                // This line is needed for iconv implementations that do not
603
                // omit characters that do not exist in the target character set
604
                ($r === $c && self::unsafeIconv($encoding, 'UTF-8//IGNORE', $r) !== $c)
605
            ) {
606
                // Reverse engineer: what's the UTF-8 equiv of this byte
607
                // sequence? This assumes that there's no variable width
608
                // encoding that doesn't support ASCII.
609
                $ret[self::unsafeIconv($encoding, 'UTF-8//IGNORE', $c)] = $c;
610
            }
611
        }
612
        $encodings[$encoding] = $ret;
613
        return $ret;
614
    }
615
}
616
617
// vim: et sw=4 sts=4
618